Mutations in CCR5 Gene May Worsen Hepatitis C Infection
Mutations in the cell receptor gene CCR5, which is "essential" for HIV to enter a cell, are more common in people with hepatitis C infections than in the general population, according to German researchers who reported their study findings at the 8th Conference on Retroviruses and Opportunistic Infections, the Los Angeles Times reports (Maugh, Los Angeles Times, 2/7). About 1% of the population -- mostly Caucasians -- inherits a double mutation of the gene that usually confers resistance against HIV infection. And although individuals with a single mutation can still become infected with the virus, progression to AIDS is usually slowed by about two years, compared to those with no mutation. Dr. Rainer Woitas and his team from the University of Bonn studied the mutations in four groups: 153 people with only hepatitis C, 102 people with only HIV, 130 people with both infections and 102 blood donors with no known infections who served as controls. Woitas' team found that individuals with the double mutation were protected from HIV infection, but also that 7.8% of those infected with hepatitis C had the mutation, a rate that was three times more common than expected. In addition, hepatitis C patients with the mutation had levels of that virus in their bloodstream that were four times higher than in individuals without the mutation. Higher levels of virus usually mean that patients progress more rapidly, although Woitas' study was not designed to test outcomes (Altman, New York Times, 2/7). Dr. David Ho of the Aaron Diamond AIDS Research Center in New York City said, "This is certainly a novel observation," adding that the findings highlight the "way genetic differences between people affect the progression of AIDS," according to the Los Angeles Times.
Woitas' findings could have implications for a new class of drugs that are not yet approved for marketing. The drugs, called entry inhibitors, "mimic" the mutations in CCR5 to disable the gene so HIV is unable to use the receptor to enter the cell. Woitas warned that using these drugs in people infected with hepatitis C "would likely only exacerbate the hepatitis C infection." The researchers said that further study was needed, as the mechanism of the mutation on hepatitis C remains unknown (Los Angeles Times, 2/7).